Electric switch



Feb. 26, 1935. us 1,992,922

ELECTRIC SWITCH Filed May 22, 1933 In1 39 mm w, Mr W W! I IN HD HI J W gwumm .1 iii/laws Patented Feb. 26,1935

UNITED STATES PATENT. OFFICE This invention relates to electric switches and has special reference to a switch for the starting motors of automobiles and the like.

In switches of this character it is usual to pro- 5 vide an operating plunger which closes the switch when depressed and which is normally held in raised position by a spring so that the switch is normally open. It is common to use, for this purpose, a coiled compression spring which surrounds the portion of the plunger which protrudes from the switch casing or housing and which bears against said casing at one end and at its other end against a collar forming a spring seat and carried by the plunger.

One important object of the present invention is to provide an improved form of switch wherein the collar and means for securing it in position on the plunger are novel and which avoids the difiiculties attendant on collars which are primed on and collars of the so called C-shape which are now in use.

In switches of this character it is quite common to providea casing of triangular prismatic form, the casing resting in use with one side of the triangular prism bearing against the support to which the switch is attached. It is usual to line at least a portion of such casings with insulation and it is desirable to have such insulation in a single piece when possible. Triangular prismatic casings have not heretofore been lined with insulation in a single strip owing to difficulties in fitting a single strip lining in such a shape of casing.

A second important object of the invention is to provide an improved arrangement of switch having a triangular prismatic casing wherein a single strip of insulation of novel form and arrangement constitutes the lining.

In switches of this character it is usual to provide a fixed contact piece in the path of a second contact carried by the plunger. Such fixed contact pieces have usually been rigid and irremovably fixed to a stud to which the conductor cable is connected. Such constructions are open to a number of mechanical objections and a third important object of the invention is to provide a novel and improved contact arrangement for such a switch wherein yielding of the fixed contact may take place and also wherein the contact piece may be removed and replaced with great ease and without the necessity of disassembling any other parts.

With the above and other objects in view, the invention consists in general of certain novel details of construction and combinations of parts hereinafter fully described, illustrated in the ac,-

companying drawing and specifically claimed.

In the accompanying drawing, like characters of reference indicate like parts in the several views, and:- ii

Figure 1 is a transverse section through a switch constructed in accordance with this invention; v

Fig. 2 is a side elevation of one form of plunger as used herewith; I

Fig. 3 is a side elevation of a second form of such plunger;

Fig. 4 is a vertical section through a die arrangement showing a plunger and its collar with the die arrangement in position to effect securing of the collar to the plunger;

Fig. 5 is a plan view of the blank of insulating material from which the lining for the casing is formed;

' Fig. 6 isa side elevation of a contact the contact piece applied;

, Fig. 7 is a top plan view of the parts shown in Fig. 6.

Fig. 8 is a view showing a modified manner of constructing the plunger and spring seat or washer.

In the embodiment of the invention here shown there is provided a triangular prismatic casing or housing having .an inclined front wall 10, an oppositely inclined rear wall 11, and end walls 12. This casing is open on its under side where it rests against a supporting surface when in-use.

Projecting from the front wall is a nipple 13 wherein is slidably mounted a plunger 14 having a reduced lower end 15 formingan abrupt shoulder at the junction of this end and the body of the plunger. This reduced end is located within the casing and on it is mounted one or more insulating washers 16 which are supported in position by the shoulder. These washers are of greater diameter than the opening in the nipple so as to prevent too great protraction of the plunger. On the end 15, below the washers 16, are insulating washers 1'? which fit in an opening formed in a rectangular contact plate 18 hav ing upturned or bevelled ends 19. Below and resting against the plate 18 on the end 15 is an insulating washer 20. The terminal portion of the end 15 is further reduced and has fitted thereon a keeper washer 21, the terminal portion being riveted over on this washer as at 22 to keep all these washers and the contact plate securely held together on the end 15 with the contact plate insulated from the plunger. and casing while'having sufficient play or looseness to permit tilting stud with phosphor bronze. 40'

of the plate 18 on operation of the plunger to make even contact with the contacts 36 and 46.

On the protruding part of the plunger 14 is formed a circumferential groove which is shown in Figure 3 at 23 as of rectangular form in crosstightly in said groove and the cup washer is thus firmly supported in its attachment to the plunger. This upsetting of the washer nipple may be conveniently accomplished by the apparatus shown in Figure 4. In this apparatus there is provided an anvil 2'7 whereon rests a. block' 28 having an opening in its center in which may be fitted the outer end of the plunger with the groove just above the upper face ofv the block. The cup Washer, in its prepared condition, is fitted on the plunger to rest on top of the block 28. A die 29 having a central bore and a cupped lower end is now forced down against the nipple which is compressed vertically and is thus forced solidly into the groove.

A coiled compression spring 26' surrounds the plunger 14 and nipple 13 between the wall 10 and cup washer and holds the plunger normally wherethrough extends'a stud 30 having a rectan'gul'ar head 31 on its lower end. This stud carries on its lower end a contact member formed of a strip of conductive metal such as copper or This contact member has a stud' engaging portion 32 slotted as at 33 tofit over the stud. The ends'of the arms of this slotted or yoke portion are bent down as at 34 to bear against the side of the head 31 and thus prevent the contact member from slipping off and hold it against rotation on the stud. This contact member has a portion 35 extending downwardly from the rear end of the yoke and from the lower end of the portion 35 extends an angularly bent portion 36 which has its terminal part substantially parallel to the upper one of the ends 19. The angularly bent portion 36 lies'in spaced relation to the head 31 so that, when the plunger is forced down, it may spring slightly and assume full contacting position with the end 19 when the plunger 14 is forced down. Thereby all sparking and improper contacting between the two contacts is prevented. The stud and its contact are insulated from the wall 11 on the inside of the housing by a special one piece insul-ator formed of a strip of foldable insulating material of trapezoidal form having a rectangular central portion 37 provided with a central open-. ing 38 through which the studpasses. Oppositely bevelled ends 39 are defined from this central portion by fold lines 40 and these ends are, in use, bent at right angles to the central portion and lie against the inner surfaces of the end walls this arrangement. A metallic washer 42 is fitted on the stud on top of the washer 41 and a clamping nut 43 is screwed'on the stud, which has its outer end threaded, and clamps the contact, insulation members, metallic washer and stud firmly in place. A binding nut 44 and washer 45 on the stud serve as means to secure the usual eyed 7 cable end to the stud.

A ground contact 46 is secured within the casing to the casing supporting member by a stud and nut 47 and lies in the path of the remaining end 19. Ordinarily the contact member 46 is assembled on the outer surface or adjacent to the starting motor, and therefore need not be considered a part of the switch herein described. Obviously, the plate 13 be directly connected to the plunger so that grounding is effected, on

closing the switch, through the plunger and casing. 'With such an arrangement the contact 46 may be omitted. a g In Fig. 8, the plunger 14 is provided with a reduced end 48 and the washer 25 is replaced by a cup washer 48 having a central opening'toreceive the end 48. After placing the washer. on the reduced end 48 the latter is rivetted over on the washer 49 to secure the washer to the plunger 14.

There has thus been provided a'simplc and efficient device ofthe kind described and for the purposes specified. 1

It is obviousthat changes may be made in the form and construction of the invention without departing from the material principle involved. It is not therefore desired to confine the invention to the exact construction herein shown and described, but it is desired to include all such as properly come within the scope claimed.

What I claim is:

1. In a switch of thekincl described, a casing, a fixed contact in said casing, a plunger slidably mounted to project through said casing and having a movable contact fixed to its lower end to be moved by the plunger into and. out of contact with the fixed, contact, a circularly continuous cup Washer on the outwardly projecting portion of the plunger having an opening through which the plunger passes, said washer having a bead formed atthe edge of said opening, said plunger having a circumferential groove into which said beaded edge tightly fits, and a spring surrounding the plunger and fitting atone end into said cup washer and at its other end bearing against the casing.

2. In a switch of the kind described, a casing, a fixed contact in said casing, a plunger slidably mounted to project through said casing and having a movable contact fixed to its lower end to be moved by the plunger'into and out of contact with the fixed contact, a circularly continuous cup washer on the outwardly projecting portion of the plunger having an opening through which the plunger passes, said washer having a bead formed at the edge of said opening, said plunger having acircumferential groove into which said beaded edge tightly fits, a spring surrounding the plunger and fitting at one end into said cup washer and at its other end bearing against the casing, and a nipple formed on said casing and having the plunger slidable therein, said nipple fitting into the end of the spring. 7

3. In a switch of the kind described, a casing, a fixed contact insaidcasing, a plunger slidably mounted to project through said casing and having a movable contact fixed to its lower end to be moved by the plunger into and out of contact with the fixed contact, a cup washer on the outwardly projecting portion of the plunger having an opening through which the plunger passes, said washer having a bead formed at the edge of said opening, said plunger having a circumferential groove into which said beaded edge tightly fits, a spring surrounding the plunger and fitting one end into said cup washer and at its other end bearing against the casing, and an insulating plate within said casing having its central portion secured between the fixed contact and the casing and having end portions extending in parallelism on opposite sides of the movable contact, said end portions forming guide means for the movable contact whereby to prevent engagement of the casing walls by said movable contact.

4. In a switch of the kind described, a casing, a fixed contact in said casing, a plunger slidably mounted to project through said casing and having a movable contact fixed to its lower end to be moved by the plunger into and out of contact with the fixed contact, a cup washer on the outwardly projecting portion of the plunger having an opening through which the plunger passes, said washer having a bead formed at the edge of said opening, said plunger having a circumferential groove into which said beaded edge tightly fits, a spring surrounding the plunger and fitting at one end into said cup washer and at its other end bearing against the casing, a nipple on said casing and having the plunger slidable therein, said nipple fitting into the end of the spring, and an insulating plate within said casing having its central portion secured between the fixed contact and the easing and having end portions extending in parallelism on opposite sides of the movable contact, said end portions forming guide means for the movable contact whereby to prevent engagement of the casing walls by said movable contact.

5. In a switch of the kind described, a casing, a fixed contact in said casing, a plunger slidably mounted to project through said casing and having a movable contact fixed to its lower end to be moved "by the plunger into and out of contact with the fixed contact, a cup washer on the outwardly projecting portion of the plunger having an opening through which the plunger passes, said washer having a bead formed at the edge of said opening, said plunger having a circumferential groove into which said beaded edge tightly fits, thecircumferential groove having its lower wall bevelled and its upper wall at right angles to the axis of the plunger and the bead fitting tightly against both the said walls.

ABRAHAM S. PINKUS. 

